RODI Pressure Loss

jhatfield · May 12, 2016

Looking for ideas on how to troubleshoot pressure loss on an RO/DI which has been running since February. It's a BRS 75gpd unit which has been running great at around 60psi up until a couple weeks ago when it dropped to 30psi. It went from making 1 gal every 15 min to 1 gal every 30 min (roughly).

I noticed that the sediment filter was getting a little brown so I switched that out with a new one with no improvement in pressure. Also replaced the carbon block and flushed the RO membrane... no dice.

When it was running at 60psi I did notice that it would briefly drop to 30 a couple times a minute and then would shoot right back up to 60psi. It stays at a constant 30psi now with no fluctuations what so ever.

Ideas?

AZDesertRat · May 12, 2016

Get a hose bib pressure gauge in the garden dept at the hardware store and see what you have coming in. If you have a pressure regulator on your home check the adjustment, the sometimes go bad.
What is the RO/DI hooked up to, if it is a self piercing needle valve they are famous for plugging or not being pierced completely. If it is a faucet adapter try disconnecting it and cleaning everything.
Check your waste ratio, if it has increased then pressure available to the membrane goes down. Try crimping the waste line closed temporarily and see if the pressure goes up.

CodyRVA · May 12, 2016

Water source?

jhatfield · May 12, 2016

Thanks all! I have the RODI hooked up to a hose bib in the backyard. Basically, I have a small garden storage shed/closet with the RO/DI supply running from a hose bib.

When I get home today I'll disconnect and clean then I'll check the waste ratio. Also, I'm going to check the hose bib itself because I have an identical one set up for the hose and (in hindsight) there is a pressure issue with that as well.

jhatfield · May 19, 2016

Update:

Somehow the pressure has increased up to 65psi. This happened right after I installed a ball valve on the DI output to test if the auto shut off would stop the waste flow. With the valve closed it took a few minutes for the waste flow to stop and then the pressure slowly rose to 65psi. Now it stays in the 60psi neighborhood except when someone flushes the toilet; then it drops to below 30 and stays there quite a while after the toilet has finished filling.

Also the clean to waste ratio is 1:2 not the 1:4 I expected. Takes about 13minutes per gallon. It was operating at 1:4 when I first installed it up until a few weeks ago. TDS reads 0 on the output. Wondering if there is a problem with the RO membrane. Ideas?

abinder · May 19, 2016

Is that 1:2 "good water : waste water" ?

Reef Junky150 · May 19, 2016

I had a sadle valve clog once.

AZDesertRat · May 19, 2016

Sounds like your hose bib location is not optimal. Try hooking it up closer to your water meter or incoming water to see if the pressure still drops when something else is running. Flushing a toilet should not drop pressure that much if your internal plumbing is sized correctly and you have no pressure regulator or restrictions. I would also check you house valve and water meter to make sure they are on all the way.